In A NEW HOPE vader says something about feeling a precencse he hasn't felt in some time , or something to that effect. At the time the movie was released it was Kenobi he felt in the force but since the release of Revenge of the sith , It could also mean that he felt luke. I would assume that when padme was carrying the babies anakin could feel them in the force and I just figure that luke was a little Brighter in the force so anakin would have fely him and Leia would have been shadowed . There for vader feeling luke on the death star in ANH and his also not recognizing Leia when she was his prisoner on the death star. I know its easy to make a conection looking back but It does fit . What do you guys think ?